Systems and methods for actuating end effectors to condition polishing pads used for polishing microfeature workpieces

ABSTRACT

Systems and methods for activating end effectors used to condition microfeature workpiece polishing pads are disclosed. A system in accordance with one embodiment of the invention includes a rotatable end effector having a conditioning surface configured to condition a microfeature workpiece polishing medium, and a driver coupled to the end effector to rotate the end effector. The driver does not include a flexible, continuous belt coupled to the end effector. For example, the driver can include a motor-driven worm meshed with a worm gear. The system can further include a forcing element coupled to the end effector to apply a force to the end effector that is at least approximately normal to a conditioning surface of the end effector. The forcing element can include a first generally rigid member and a second generally rigid member coupled to the end effector and movable relative to the first generally rigid member to apply the force.

TECHNICAL FIELD

The present invention relates generally to systems and methods foractuating end effectors for conditioning polishing pads used to polishmicrofeature workpieces.

BACKGROUND

Mechanical and chemical-mechanical planarization and polishing processes(collectively “CMP”) remove material from the surfaces of microfeatureworkpieces in the production of microelectronic devices and otherproducts. FIG. 1 schematically illustrates a rotary CMP machine 10having a platen 22, a polishing pad 20 on the platen 22, and a carrier30 adjacent to the polishing pad 20. The CMP machine 10 may also have anunder-pad 23 between an upper surface 26 of the platen 22 and a lowersurface of the polishing pad 20. A platen drive assembly 24 rotates theplaten 22 (as indicated by arrow F) and/or reciprocates the platen 22back and forth (as indicated by arrow G). Because the polishing pad 20is attached to the under-pad 23, the polishing pad 20 moves with theplaten 22 during planarization.

The carrier 30 has a carrier head 31 with a lower surface 33 to which amicrofeature workpiece 12 may be attached, or the workpiece 12 may beattached to a resilient pad 32 under the lower surface 33. The carrierhead 31 may be a weighted, free-floating wafer carrier, or a carrieractuator assembly 34 may be attached to the carrier head 31 to impartrotational motion to the microfeature workpiece 12 (as indicated byarrow J) and/or reciprocate the workpiece 12 back and forth (asindicated by arrow I).

The polishing pad 20 and a polishing solution 21 define a polishingmedium 25 that mechanically and/or chemically-mechanically removesmaterial from the surface of the microfeature workpiece 12. Thepolishing solution 21 may be a conventional CMP slurry with abrasiveparticles and chemicals that etch and/or oxidize the surface of themicrofeature workpiece 12, or the polishing solution 21 may be a “clean”nonabrasive planarizing solution without abrasive particles. In most CMPapplications, abrasive slurries with abrasive particles are used onnonabrasive polishing pads, and clean nonabrasive solutions withoutabrasive particles are used on fixed-abrasive polishing pads.

To planarize the microfeature workpiece 12 with the CMP machine 10, thecarrier head 31 presses the workpiece 12 face-down against the polishingpad 20. More specifically, the carrier head 31 generally presses themicrofeature workpiece 12 against the polishing solution 21 on apolishing surface 27 of the polishing pad 20, and the platen 22 and/orthe carrier head 31 move to rub the workpiece 12 against the polishingsurface 27. As the microfeature workpiece 12 rubs against the polishingsurface 27, the polishing medium 25 removes material from the face ofthe workpiece 12.

The CMP process must consistently and accurately produce a uniformlyplanar surface on the microfeature workpiece 12 to enable precisefabrication of circuits and photo-patterns. One problem with existingCMP methods is that the polishing surface 27 of the polishing pad 20 canwear unevenly or become glazed with accumulations of polishing solution21 and/or material removed from the microfeature workpiece 12 and/or thepolishing pad 20. To restore the planarizing/polishing characteristicsof the polishing pad 20, the pad 20 is typically conditioned by removingthe accumulations of waste matter with a conditioner 40. Suchconditioners are available from Applied Materials of Santa Clara, Calif.under the trade name Mirra.

The existing conditioner 40 typically includes an abrasive end effector41 having a head 45 generally embedded with diamond particles. The head45 is attached to a single shaft 42 which connects to a shaft housing72. The shaft housing 72 is supported relative to the polishing pad 20by an arm 43 and a support housing 44. A motor 51 within the supporthousing 44 rotates the shaft housing 72, the shaft 42 and the head 45(as indicated by arrow A) via a pair of pulleys 53 a, 53 b and aconnecting belt 54. The conditioner 40 can also include a separateactuator (not shown in FIG. 1) that sweeps the arm 43 and the endeffector 41 back and forth (as indicated by arrow B). A bladder 71rotates with the shafts 42 and applies a normal force to the head 45 (asindicated by arrow C) to press the head 45 against the polishing pad 20.In another arrangement (available from Ebara Corporation of Tokyo,Japan), a non-rotating air cylinder counteracts the dead weight of thehead 45 to regulate the down-force applied against the polishing pad 20.In either arrangement, the typical end effector 41 removes a thin layerof the polishing pad material in addition to the waste matter to form anew, clean polishing surface 27 on the polishing pad 20.

One drawback associated with the arrangements described above withreference to FIG. 1 is that the drive belt 54 typically wears out at arelatively rapid rate, Accordingly, the operator of the CMP machine 10must spend a significant amount of time replacing the belt 54, whichreduces the throughput of the machine 10. Furthermore, as the belt 54wears and fails, it can contaminate the polishing pad 20 with debris,which can interfere not only with the conditioning operation but alsowith the polishing operations conducted on the polishing pad 20. Stillfurther, when the machine 10 is operated in an autonomous manner, thebelt 54 can fail without an automatic provision for halting the sweepingaction of the arm 43. As a result, the head 45 can sweep back and forthwithout rotating, which can condition the polishing pad in an unevenmanner and/or create an uneven wear pattern on the abrasive surface ofthe head 45.

Another drawback associated with the system described above withreference to FIG. 1 is that the bladder 71 (used to apply a normal forceto the head 45) can fail after a relatively short duty cycle, furtherincreasing the amount of time and money required to keep the machine 10operational. Still further, the operator must often over-pressure thebladder 71 to overcome a threshold inflation resistance, and then reducethe pressure to apply the desired force. This can result in inconsistentdown-forces applied to the polishing pad 20, which can in turn lead toinconsistent polishing pad conditions, and ultimately, inconsistentsurface conditions on the workpiece 12.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially schematic, side elevation view of a CMP systemhaving a conditioner arranged in accordance with the prior art.

FIG. 2 is a partially schematic, isometric illustration of a CMP systemhaving a conditioner that is actuated in accordance with an embodimentof the invention.

FIG. 3 illustrates a system having a motor coupled to an end effector inaccordance with another embodiment of the invention.

FIG. 4 illustrates a system having a drive shaft coupled between an endeffector and a motor in accordance with still another embodiment of theinvention.

FIG. 5 illustrates a system having a chain coupled between an endeffector and a motor in accordance with yet another embodiment of theinvention.

FIG. 6A illustrates a system having an end effector rotatably driven byan impeller in accordance with still a further embodiment of theinvention.

FIG. 6B illustrates a system having an end effector rotatably driven bya motor in accordance with yet another embodiment of the invention.

FIG. 7 illustrates a portion of a system having a piston and cylinderarrangement for applying a normal force to an end effector in accordancewith an embodiment of the invention.

FIG. 8 illustrates a system having a rack and pinion arrangement forapplying a normal force to an end effector in accordance with stillanother embodiment of the invention.

DETAILED DESCRIPTION

The present invention is directed toward systems and methods foractuating end effectors used to condition polishing pads that are inturn used to polish microfeature workpieces. A system in accordance withone aspect of the invention includes a rotatable end effector having aconditioning surface configured to condition a microfeature workpiecepolishing medium, and a driver coupled to the end effector to rotate theend effector. The driver does not include a flexible, continuous beltcoupled to the end effector. For example, the driver can instead includea first gear (e.g., a worm) coupled to a motor, and engaged with asecond gear (e.g., a worm gear) coupled to the end effector. In otherembodiments, the driver can include a rotatable impeller in fluidcommunication with a conduit that is coupleable to a source of highpressure fluid. In still a further embodiment, the drive link caninclude a drive chain coupled between the end effector and a motor.

A system in accordance with another aspect of the invention can includea rotatable end effector having a conditioning surface configured tocondition a microfeature workpiece polishing medium, a driver coupled tothe end effector to rotate the end effector, and a forcing elementcoupled to the end effector. The forcing element can include a firstgenerally rigid member and a second generally rigid member. The secondgenerally rigid member can be coupled to the end effector, and can beoperatively coupled to the first generally rigid member. At least one ofthe members can be movable relative to the other to apply a force to theend effector that is at least approximately normal to the conditioningsurface. At least one of the members can also rotate with the endeffector. In a particular aspect of the invention, at least one of thefirst and second generally rigid members includes a cylinder and theother includes a piston received in the cylinder and slidable along amotion axis relative to the cylinder.

The invention is also directed toward methods for making and usingsystems for conditioning microfeature workpiece polishing pads. In oneaspect of the invention, a method for retrofitting a system havingfeatures for conditioning microfeature workpiece polishing mediaincludes removing a flexible, continuous belt coupled between an endeffector and a motor, wherein the end effector has a conditioningsurface configured to condition a microfeature workpiece polishingmedium. The method can further include coupling a driver to the endeffector to rotate the end effector, wherein the driver does not includea flexible, continuous belt coupled to the end effector. For example,the method can include connecting a first gear to the motor, connectinga second gear to the end effector, and coupling the first gear to thesecond gear without a flexible, continuous belt.

A method for operating a system having features for conditioningmicrofeature workpiece polishing media can include contacting aconditioning surface of an end effector with a polishing medium andapplying an at least approximately normal force to the polishing mediumwith the conditioning surface by moving at least one generally rigidmember of a forcing mechanism coupled to the end effector relative to asecond generally rigid element of the forcing mechanism. The method canfurther include rotating the end effector and at least one of thegenerally rigid members together relative to the polishing medium.

As used herein, the terms “microfeature workpiece” and “workpiece” referto substrates on and/or in which microelectronic devices are integrallyformed. Typical microdevices include microelectronic circuits orcomponents, thin-film recording heads, data storage elements,microfluidic devices, and other products. Micromachines andmicromechanical devices are included within this definition because theyare manufactured using much of the same technology that is used in thefabrication of integrated circuits. The substrates can be semiconductivepieces (e.g., doped silicon wafers or gallium arsenide wafers),nonconductive pieces (e.g., various ceramic substrates) or conductivepieces. In some cases, the workpieces are generally round, and in othercases the workpieces have other shapes, including rectilinear shapes.Several embodiments of systems and methods for conditioning polishingmedia are described below. A person skilled in the relevant art willunderstand, however, that the invention may have additional embodiments,and that the invention may be practiced without several of the detailsof the embodiments described below with reference to FIGS. 2-8.

FIG. 2 is a partially schematic, isometric illustration of a CMP system110 having a conditioner 140 that is activated in accordance with anembodiment of the invention. The conditioner 140 can include a supporthousing 144, an arm 143 extending outwardly from the support housing144, and an end effector 141 carried by the arm 143. The end effector141 can be rotated by a driver 150 that does not include a belt coupledto the end effector 141. Accordingly, embodiments of the conditioner 140can condition microfeature workpiece polishing pads without some or allof the drawbacks described above with reference to FIG. 1. Furtherdetails of these embodiments are described below.

The end effector 141 can include a conditioning head 145 having aconditioning surface 146. The conditioning surface 146 can have abrasiveelements (e.g., diamond particles) that rub against a polishing padduring operation. The conditioning head 145 can be coupled to two shafts142 extending into a housing 172. A forcing device 170 positioned withinthe housing 172 can apply a normal force to the conditioning head 145via the shafts 142 (as indicated by arrow C), along an actuation axis147. A housing carriage 173 can support the housing 172 relative to thearm 143: Further details of the forcing device 170 are described belowwith reference to FIG. 7.

The housing 172 and the end effector 141 can also rotate about theactuation axis 147 (as indicated by arrow A) when the driver 150 isactivated. Accordingly, the driver 150 can include a motor 151 coupledto the end effector 141 with a drive link 152. In a particularembodiment shown in FIG. 2, the drive link 152 can include a first gear155 a (e.g., a worm) engaged with a second gear 155 b (e.g., a worm gearor ring gear) carried by the housing 172. A signal link 156 (e.g., acable bundle) provides power and control signals to the motor 151 todirect the rotational motion of the end effector 141.

One feature of an embodiment of the CMP system 110 shown in FIG. 2 isthat the drive link 152 does not include a continuous, flexible beltcoupled between the motor 151 and the end effector 141. An advantage ofthis feature is that the system 110 may operate for longer periods oftime than existing systems before the drive link 152 requiresmaintenance. For example, the gears 155 a, 155 b can be manufacturedfrom wear-resistant metals and/or plastics to significantly increase theexpected life span of these components. A further advantage of thisfeature is that the wear resistant gears 155 a, 155 b (and, optionally,other components of the drive link 152) are less likely to shedparticles during use and are accordingly less likely to interfere witheither pad conditioning operations or workpiece polishing operations.

Still another feature of an embodiment of system 110 shown in FIG. 2 isthat the drive link 152 can be retrofitted onto existing systems (e.g.,the system 10 described above with reference to FIG. 1) with relativelylittle effort. For example, the housing carriage 173 can be partiallycut away (as shown in FIG. 2) and the pulley originally carried by thehousing 172 can be replaced with the second gear 155 b. The motor 151can be the same motor as the motor 51 shown in FIG. 1, simplyrepositioned and coupled to the first gear 155 a, then mounted to thearm 143 to provide a more direct coupling with the end effector 141. Ina particular embodiment, the motor 151 and associated motor controllerare available from Yaskawa Motors of Tokyo, Japan. In a particularaspect of this embodiment, the gear reduction box normally provided withsuch motors can be eliminated because the gears 155 a, 155 b providesufficient gear reduction (e.g., 20:1). An advantage of this feature isthat it can significantly reduce the time and cost associated withretrofitting existing systems with a drive link that does not include aflexible belt.

In one embodiment, the system 110 shown in FIG. 2 can include a detector164 coupled to the motor 151 to detect a change in the electrical energydrawn by the motor 151. The system 110 can also include a controller 165operatively coupled to the detector 164 and the motor 151 to control theoperation of the motor 151 based on signals received from the detector164. For example, the detector 164 can detect a change in the currentand/or power drawn by the motor, and the controller 165 can halt themotor when the change differs from a threshold value by more than aselected amount. In a particular embodiment, a reduction in currentdrawn by the motor 151 can indicate that the drive link 152 has failed.This operation can occur regardless of the nature of the drive link 152.Accordingly, this aspect of the system 110 can be applied to drive linksgenerally similar to those described above the reference to FIG. 1, aswell as those described with reference to FIGS. 2-8.

In another aspect of this embodiment, the change in the electricalenergy drawn by the motor 151 can correspond to a condition other than afailure of the drive link 152. For example, such a change can correspondto a failure of the forcing device 170. In a particular embodiment, areduction of current drawn by the motor 151 can correspond to anabnormal reduction in the downforce applied by the forcing device 170.In any of the foregoing embodiments, the system 110 can signal theoperator to indicate a failure or abnormal condition, and/or canautomatically halt motion of the end effector 141. The end effectormotor can include rotation about the actuation axis 147 (as indicated byarrow A), and/or a sweeping motion of the arm 143 (as indicated by arrowB).

In still another aspect of this embodiment, the change in the electricalenergy drawn by the motor 151 can correspond to a change in thecondition of the polishing pad being conditioned by the conditioner 140.For example, the amount of texture at the surface of the polishing padcan be an important factor in determining whether or not the polishingpad has been adequately conditioned. Because it typically requires morepower to move the end effector 141 over a rough polishing pad than overa smooth polishing pad, the amount of power drawn by the motor 151 canindicate whether the polishing pad has been sufficiently roughened bythe conditioning operation.

FIGS. 3-6 illustrate CMP systems having drive links configured inaccordance with further embodiments of the invention. Referring first toFIG. 3, a system 310 can include a conditioner 340 positioned proximateto a polishing pad 320. The polishing pad 320 can be supported by aplaten 322 or other support, optionally with an underpad 323 positionedbetween the platen 322 and the polishing pad 320. A drive assembly 324can rotate the platen 322 and the polishing pad 320 (as indicated byarrow F) and translate the platen 322 and the polishing pad 320 (asindicated by arrow G). A polishing liquid 321 can be disposed on thepolishing pad 320, and the polishing pad 320 (with or without thepolishing liquid 321) can form a polishing medium 325 for removingmaterial from a microfeature workpiece 312.

A microfeature workpiece 312 can be supported relative to the polishingpad 320 with a carrier 330. Accordingly, the carrier 330 can include acarrier head 331 and, optionally, a resilient pad 332 that supports theworkpiece 312 relative to the polishing pad 320. The carrier 330 caninclude a carrier actuator assembly 334 that translates the carrier head331 and the workpiece 312 (as indicated by arrow I) and/or rotates thecarrier head 331 and the workpiece 312 (as indicated by arrow J). Therelative movement between the polishing pad 320 and the workpiece 312chemically and/or chemically-mechanically removes material from thesurface of the workpiece 312 during polishing and/or planarization.

The conditioner 340 can condition the polishing pad 320 before, after,and/or during the polishing operation. The conditioner 340 can include adrive link 350 that, like the drive link 150 described above withreference to FIG. 2, does not include a continuous flexible belt.Instead, the drive link 350 can include a first gear 355 a carried by amotor 351 and meshed with a second gear 355 b carried by the housing172. In this particular embodiment, the gears 355 a, 355 b can includestraight-cut or helical-cut gears, and the axis of rotation of the firstgear 355 a can be parallel to the axis of rotation of the second gear355 b. An advantage of this arrangement is that it may be suitable formotors 351 that do not require a significant gear reduction to drive theend effector 141. Conversely, an advantage of the arrangement describedabove with reference to FIG. 2 is that the worm 155 a and worm gear 155b can provide a significant gear reduction for a high-speed motor 151.

FIG. 4 is a partially schematic illustration of a CMP system 410 havinga drive link 450 that rotates the end effector 141 in accordance withanother embodiment of the invention. In one aspect of this embodiment,the drive link 450 can include a motor 451 positioned in the supporthousing 144 to rotate a first gear 455 a. The end effector 141 caninclude a second gear 455 b, and a drive shaft 457 can transmit rotarymotion between the first gear 455 a and the second gear 455 b.Accordingly, the drive shaft 457 can carry a third gear 455 c meshedwith the first gear 455 a, and a fourth gear 455 d meshed with thesecond gear 455 b. The third and fourth gears 455 c, 455 d can includeworms (as shown in FIG. 4) or other gear arrangements (e.g., bevelgears).

FIG. 5 illustrates a CMP system 510 having a drive link 550 configuredin accordance with yet another embodiment of the invention. In thisembodiment, the drive link 550 includes a motor 551 carried in thesupport housing 144 and connected to a first sprocket 555 a. A secondsprocket 555 b is carried by the end effector 141, and is driven by thefirst sprocket 555 a via a chain 557. The chain 557 can includemultiple, generally rigid segments that are pivotably connected to eachother. Accordingly, the motor 551 can drive the end effector 141 withoutthe drawbacks associated with the flexible continuous belt shown in FIG.1.

In still further embodiments, at least a portion of the drive linkpowering the end effector can include a fluid coupling. For example,referring now to FIG. 6A, a system 610 in accordance with anotherembodiment of the invention can include a drive link 650 a that providesa fluid (e.g., hydraulic or pneumatic) driving force. Accordingly, theend effector 141 can include an impeller 658 positioned within animpeller channel or housing 659 and coupled to the shafts 142. A fluidconduit 660 having a nozzle 661 directs high pressure fluid to theimpeller 658 to rotate the impeller 658 and the conditioning head 145.Fluid can be supplied to the fluid conduit 660 from a high pressurefluid supply 663, and can be controlled with a valve 662. The fluid canbe returned to the high pressure fluid supply 663 via a return line andpump (not shown in FIG. 6A), for example, when the fluid includes aliquid. The fluid can be exhausted to the atmosphere (or optionallyrecycled) when the fluid includes air or another suitable gas.

FIG. 6B illustrates another embodiment of the system 610 having anotherarrangement for rotating the conditioning head 145. In one aspect ofthis embodiment, the system 610 can include a drive link 650 b that inturn includes one or more fixed members 666 (e.g., electrical coils)that depend from the arm 143, and one or more rotating members 667(e.g., magnets) that depend from the rotating housing 659. When acurrent is applied to the fixed members 666, it induces a current in therotating members 667 to rotatably drive the conditioning head 145. Thefirst and second members 666, 667 can be integrated into a motor, forexample, a direct drive motor, including a Megatorque motor, availablefrom NSK Ltd., of Tokyo, Japan.

One feature of the foregoing arrangement is that it can eliminate gears,pulleys, belts, chains and other mechanical drive elements. An advantageof this feature is that it can be simpler to install and maintain, andcan be less likely to generate particulates, which can contaminate thepolishing pad 320 (FIG. 3). Another advantage of this feature is that itcan reduce the noise associated with mechanical drive elements, whichmight otherwise have adverse effects on feedback signals, includingthose used to determine the status of the polishing pad 320, the drivelink 650 b and/or the microfeature workpiece 312 (FIG. 3) processed bythe system 610.

FIGS. 7 and 8 illustrate further details of the forcing element 170identified above with reference to FIG. 2 in accordance with furtherembodiments of the invention. As shown in FIG. 7, the forcing element170 can include the housing 172 supported by the arm 143 and the housingcarriage 173. Upper and lower bearings 774 a and 774 b allow the housing172 to rotate smoothly relative to the arm 143 and the housing carriage173. The forcing element 170 can further include a first generally rigidmember 775 a and a second generally rigid member 775 b that isoperatively coupled to the first generally rigid member 775 a. At leastone of the members 775 a, 775 b is movable relative to the other toimpart an at least approximately normal force to the conditioning head145. For example, in an embodiment shown in FIG. 7, the first member 775a can include a cylinder, and the second member 775 b can include apiston that is axially movable within the cylinder (as indicated byarrow K) and is coupled to the shafts 142 of the end effector 141. One(or as shown in FIG. 7, both) of the members 775 a, 775 b can rotatewith the conditioning head 145.

In a particular aspect of this embodiment, the first rigid member 775 acan include a cylinder coupled a fluid supply line 776 that is in turnselectively coupleable to a vacuum source and a pressure source. Whenpressure is provided to the cylinder the down-force applied to theconditioning head 145 increases, and when a vacuum is applied to thecylinder, the down-force decreases. A swivel joint 777 allows theforcing element 170 to rotate relative to the fluid supply line 776.

In other embodiments, the relative positions of the first member 775 aand the second member 775 b can be altered. For example, the relativepositions can be inverted so that the cylinder is coupled to theconditioning head 145 and moves axially relative to the piston to applya force to the conditioning head 145. In other embodiments, the forceapplied to the conditioning head 145 can be regulated with otheractuator mechanisms having first and second generally rigid members. Forexample, referring now to FIG. 8, a forcing device 870 in accordancewith another embodiment of the invention can include a motor 879connected to a first rigid member 875 a (e.g., a gear or pinion). Thefirst rigid member 875 a can in turn engage a second rigid member 875 b(e.g., a rack) which is in turn coupled to the conditioning head 145.When power is supplied to the motor 879 via leads, the motor 879 can bedirected to rotate clockwise or counterclockwise to increase or decreasethe pressure applied to the conditioning head 145. In other embodiments,the forcing device 870 can have other arrangements that also apply an atleast approximately normal force to the conditioning head 145.

One feature of embodiments of the forcing devices described above withreference to FIGS. 7 and 8 is that they do not include a bladder orother flexible, inflatable device to control the pressure applied to theconditioning head 145. Instead, they include a generally rigid membersoperatively coupled to each other and movable relative to each other. Anadvantage of this arrangement is that the first and second generallyrigid members can provide a more predictable, repeatable force to theconditioning head 145. As a result, the manner in which the conditioninghead 145 conditions the polishing pad can be more easily repeated, whichcan produce more uniform polishing pad surfaces and accordingly, moreuniform surfaces on the workpieces that are engaged with the polishingpad.

Another advantage of the foregoing features is that the generally rigidcomponents may be less likely to fail than the flexible bladderdescribed above with reference to FIG. 1. As a result, the time andeffort required to service and maintain the apparatus can besignificantly reduced, which can in turn reduce the cost of processingthe microfeature workpieces.

From the foregoing, it will be appreciated that specific embodiments ofthe invention have been described herein for purposes of illustration,but that various modifications may be made without deviating from thespirit and scope of the invention. For example, features described inthe context of a particular embodiment of the invention can be combinedor eliminated in other embodiments. Any of the systems described abovewith reference to FIGS. 2 and 4-8 can include a polishing pad, workpiececarrier and associated drive assemblies, generally similar to thosedescribed above with reference to FIG. 3. Accordingly, the invention isnot limited except as by the appended claims.

1-44. (canceled)
 45. A method for manufacturing a system having featuresfor conditioning microfeature workpiece polishing media, the methodcomprising: providing a rotatable end effector having a conditioningsurface configured to condition a microfeature workpiece polishingmedium; positioning a forcing device at least proximate to the endeffector, the forcing device including a first generally rigid memberand a second generally rigid member operatively coupled to the firstgenerally rigid member, at least one of the generally rigid membersbeing movable relative to the other; and coupling the second generallyrigid member to the end effector so that movement of the at least onemember relative to the other applies an at least approximately normalforce to the conditioning surface of the end effector, and so that atleast one of the generally rigid members is rotatable with the endeffector.
 46. The method of claim 45 wherein one of the first and secondgenerally rigid members includes a cylinder and wherein the other of thefirst and second generally rigid members includes a piston slideablyreceived in the cylinder, and wherein coupling the second memberincludes coupling one of the piston and the cylinder to the endeffector.
 47. The method of claim 45 wherein positioning a forcingdevice includes positioning the forcing device so that both the firstand second generally rigid members are rotatable with the end effector.48. The method of claim 45 wherein positioning a forcing device includespositioning a rack and pinion system.
 49. A method for retrofitting asystem having features for conditioning microfeature workpiece polishingmedia, the method comprising: removing a flexible, continuous beltcoupled between an end effector and a motor, the end effector having aconditioning surface configured to condition a microfeature workpiecepolishing medium; and coupling a driver to the end effector to rotatethe end effector, wherein the driver does not include a flexible,continuous belt coupled to the end effector.
 50. The method of claim 49wherein coupling a driver includes: connecting a first gear to themotor; connecting a second gear to the end effector; and coupling thefirst gear to the second gear without a flexible continuous belt. 51.The method of claim 49 wherein coupling a drive system includes:connecting a first gear to the motor; connecting a second gear to theend effector; and engaging the first gear with the second gear.
 52. Amethod for retrofitting a system having features for conditioningmicrofeature workpiece polishing media, the method comprising: removinga flexible bladder coupled to an end effector and a motor, the endeffector having a conditioning surface configured to condition amicrofeature workpiece polishing medium, the flexible bladder beingconfigured to force the conditioning surface against the microfeatureworkpiece polishing medium; and coupling a forcing device to the endeffector, the forcing device including a first generally rigid memberand a second generally rigid member, the second generally rigid memberbeing operatively coupled to the first generally rigid member andcoupled to the end effector, at least one of the generally rigid membersbeing movable relative to the other to apply a force to the end effectorthat is at least approximately normal to the conditioning surface atleast one of the generally rigid members being rotatable with the endeffector.
 53. The method of claim 52 wherein one of the first and secondgenerally rigid members includes a cylinder and wherein the other of thefirst and second generally rigid members includes a piston slideablyreceived in the cylinder, and wherein coupling the second memberincludes coupling one of the piston and the cylinder to the endeffector.
 54. The method of claim 52 wherein positioning a forcingdevice includes positioning a rack and pinion system.
 55. A method foroperating a system having features for conditioning microfeatureworkpiece polishing media, the method comprising: contacting an endeffector with a polishing medium; rotating the end effector relative tothe polishing medium without driving a flexible, continuous belt coupledto the end effector; and moving at least one of the end effector and thepolishing medium relative to the other to condition the polishingmedium.
 56. The method of claim 55 wherein rotating the end effectorincludes rotating at least one shaft of the end effector and a headcoupled to the at least one shaft, the head having a conditioningsurface, and wherein rotating the end effector further includes:activating a motor; rotating a worm coupled to the motor; rotating aworm gear engaged with the worm and coupled to the at least one shaft ofthe end effector, the worm being engaged with the worm gear to rotatethe end effector when the motor is activated, and wherein the methodfurther comprises: forcing the conditioning surface against thepolishing medium by moving at least one rigid element of a forcingmechanism coupled to the end effector relative to a second rigid elementof the forcing mechanism to apply a force to the end effector that is atleast approximately normal to the conditioning surface.
 57. The methodof claim 55 wherein rotating the end effector includes directing a highpressure fluid against an impeller coupled to the end effector.
 58. Themethod of claim 55 wherein rotating the end effector includes:activating a motor; rotating a first gear coupled to the motor; androtating a second gear coupled to the end effector and engaged with thefirst gear.
 59. The method of claim 55 wherein rotating the end effectorincludes: activating a motor; and driving a drive chain coupled betweenthe motor and the end effector.
 60. The method of claim 55, furthercomprising: contacting a microfeature workpiece with the polishingmedium; and removing material from the microfeature workpiece by movingat least one of the polishing medium and the microfeature workpiecerelative to the other.
 61. A method for operating a system havingfeatures for conditioning microfeature workpiece polishing media, themethod comprising: contacting a conditioning surface of an end effectorwith a polishing medium; applying an at least approximately normal forceto the polishing medium with the conditioning surface by moving at leastone generally rigid member of a forcing mechanism coupled to the endeffector relative to another generally rigid member of the forcingmechanism while the generally rigid members are operatively coupled toeach other; and rotating the end effector and at least one of thegenerally rigid members together relative to the polishing medium. 62.The method of claim 61 wherein moving at least one generally rigidmember includes moving a piston within a cylinder.
 63. The method ofclaim 61 wherein moving at least one generally rigid member includesmoving a rack relative to a pinion.
 64. A method for operating a systemhaving features for conditioning microfeature workpiece polishing media,the method comprising: contacting a conditioning surface of an endeffector with a polishing medium; applying an at least approximatelynormal force to the polishing medium with the conditioning surface;rotating the end effector relative to the polishing medium with anelectric motor; and detecting a change in electrical energy drawn by themotor.
 65. The method of claim 64, further comprising halting rotationof the motor upon detecting at least a threshold change in electricalenergy drawn by the motor.
 66. The system of claim 64, furthercomprising halting rotation of the motor upon detecting that a currentdrawn by the motor is below a threshold value.
 67. The method of claim64 wherein detecting a change in electrical energy includes detecting achange in current drawn by the motor.
 68. The method of claim 64 whereindetecting a change in electrical energy includes detecting a change inpower drawn by the motor.
 69. The method of claim 64 wherein detecting achange in electrical energy drawn by the motor includes detecting afailure in a drive link between the motor and the end effector.